Lubricating oil composition



rates finite and LUBRICATING on. comosrrrors No Drawing. ApplicationDecember 29, 1951, Serial No. 264,275

Claims. (Cl. 25233.4)

This invention relates to a lubricating oil composition having increasedperformance characteristics. It is more specifically concerned withenhancing the antiweld properties of lubricating oil blends.

In the development of improved lubricating oils, rather than relyingexclusively on physical and chemical refining methods to produce adesirable product, lubricating manufacturers have resorted to the use ofvarious chemical compositions which when added to a mineral oil baseimpart desirable properties to the oil. While in some instances theadditives are employed to obviate the use of expensive operationsanother important use for additives is to provide the mineral oil basewith lubricating qualities not inherently possessed by mineral oils. Oneof the most important deficiencies of mineral oils is the inability toprovide lubrication between moving parts which develop during theiroperation contact pressures which are extremely high. In order thatmineral oil lubricants may be used as gear lubricants it is vital thatsuitable extreme pressure adducts be admixed with the mineral oil. Amultitude of types of compounds have been suggested in the prior art forthis purpose. Various compositions containing lead, sulfur, chlorine orphosphorus substituents or combinations of these substituents have foundwide use in this application. For determining the efiicacy of specificcompounds a wide variety of gear lubricant testing procedures have beendeveloped. These tests include both field service tests where actualperformance is evaluated under actual operating conditions usingautomotive vehicles and laboratory tests in which full scale axleassemblies or laboratory bench test machines are used. In employinglaboratory facilities to test gear lubricants, bench tests are usedgenerally to predict the service performance of gear lubricants. Some ofthe more widely used machines which incorporate the action of one metalsurface sliding on another are the Almen, Falex, 4-Ball, SAE and Timken.In demonstrating the instant invention a Falex machine was employed toprovide test data. In the Falex machine, test pieces consist of a inchdiameter steel journal and two V-blocks. The steel journal is held in avertical shaft by means of a brass shear pin. This journal is caused torotate at a constant speed. Two lever loading arms separately pivotedbehind the vertical spindle have self-aligning recesses in them to takethe V-blocks. The blocks are assembled in place in such a manner thatthe V notches are vertical and clamped around the steel journal, beingso mounted as to permit torque measurement. A load is applied by meansof a suitable mechanism which by means of a large ratchet wheel onrotation increases the load by squeezing the two lever loading armstogether. The load applied is registered on a loading dial which recordsthe actual load applied to the V-blocks. The machine may be adjusted2,715,3fifi Patented Aug. 9, 155

ice

so that the ratchet wheel will be turned automatically thus applying theload at a standard rate. It may also be turned manually if desired. Thetorque set up by the journal rotating against the V-blocks is indicatedby a hydraulically operated pressure gauge, the V-shaped bearing blocksand entire load applying mechanism being free to turn about the axis ofthe test journal. In evaluating a gear oil lubricant, a sample of theoil is placed in a metal oil cup and the two V-blocks and journal areimmersed in the oil.

Many different test procedures have been suggested for use with thismachine. In evaluating the lubricating composition employed in theinstant invention two tests were used, namely, the hour wear test andthe maximum load test. In the former test the machine was operated underconditions whereby a constant load was applied to the test blocks. Thenumber of teeth wear on the ratchet wheel indicate whether or not theoil under test was satisfactory. In evaluating a lubricating oilcomposition by means of the maximum wear test the ratchet wheel isautomatically turned thereby applying incremental increases in load tothe V-blocks at a standard rate. This test may be accompanied by scoringof the test surfaces or shearing of the journal or shear pin. In thisinstance the maximum load which the oil is ca pable of withstanding isused as a criterion of performance characteristics.

As it has been pointed out various types of compounds have been used asextreme pressure lubricating oil additives. Included among the availableand applicable compounds are the terpene hydrocarbons or theirderivatives which when sulfurized and phosphorized produce a compositionwhich if added to a mineral oil base would serve to increase theanti-weld properties of a mineral oil. While these materials functioneffectively as anti-wear additives, there is an optimum amount that canbe added to the mineral oil composition beyond which the small increasein effect obtained does not justify the addition of larger amounts.

It is therefore the object of this invention to enhance the anti-weldproperties of mineral oil gear lubricants by adding to a lubricating oilcomposition containing minor proportions of sulfurized and phosphorizedterpenes minor amounts of an additional beneficiating agent to the lubeoil composition thereby unexpectedly increasing the anti-weld propertiesthereof. This and other objects of the invention will become apparentfrom the following description of this invention:

In accordance with this invention it has beenfound that the anti-weldproperties of a sulfurized and phosphorized terpene-containinglubricating composition are synergistically improved by the addition ofminor amounts of an alkali metal oil soluble organic sulfonate. Althoughthe use of sulfonates as extreme pressure agents is disclosed in theprior art, sulfonates generally are employed as wetting agents inlubricating oil compositions and under these conditions do not impart anunexpected increase in the extreme pressure properties of mineral oilblends containing them. However, when these sulfonates are present in anamount between 0.5 and 5 per cent by weight and preferably about 1 percent by weight in a sulfurized and phosphorized terpene-containingmineral oil lubricant, an unexpected increase in the anti-weldproperties of the composition is obtained. To illustrate the instantinvention Falex test data were obtained on blends of mineral oil andvarying concentrations of sodium petroleum sulfonate, mineral oil blendscontaining a sulfurized and phosphorized terpene alcohol and mineral oilblends containing sulfonates and a sulfurized and phosphorized terpenealcohol. These results are shown in Table I.

TABLE I F alex test data Hour Wear \rlax. Composition Load, Tooth LoadPounds Wear 8.57 Sulfo-phosphorized terpene alcohol 91.5% mineral oilbase 800 147 500 8.5% sulfa-phosphorized terpene aloohoL. 0.5% alkalimetal petroleum sulionate 800' 80 91.0% mineral oil base 8.5%sulfo-phosphorized terpene alcoho I 1.0% alkali metal petroleumsulfonate. 800 33 2, 250 90.5% mineral oil base l 0.5% alkali metalpetroleum sulfonate" 400 seizure 900 99.59 mineral oil base 800 do 1.0%alkali metal petroleum SlllfOIlfitt-L. 400 30. 1, 200 99.0% mineral oilbase 800 seizure" 1.5% alkali metal petroleum snlfonate. 400 o.... 90098.5% mineral oil base alkali metal petroleum sulfonate" 90% mineral oilbase... 100% mineral oil base 400 900 The test results shown in Table 1demonstrate the effective action of combinations of a sulfurized andphosphorized terpene and minor amounts of an alkali metal oil solubleorganic sulfonate admixed in a mineral oil base. it is seen that themineral oil composition containing sodium petroleum sulfonate inconcentrations as high as 10% failed in the Falex hour wear test whenevaluated with an 800 lb. load. This indicates that the sulfonates aloneunder these conditions do not impart to the mineral oil base any extremepressure characteristics. However, mineral oil compositions containingonly a sulfurized and phosphorized terpene do function as extremepressure additives. However, the use of an oil soluble alkali metalorganic sulfonate in combination with a sulfurized and phosphorizedterpene improves the wear characteristics of the mineral oil compositionwith little deleterious results upon the maximum load results obtained,a phenomenon which could not be predicted from the test results obtainedwhen using each of the blend components alone in combination with amineral oil base. It is thus seen that superior performancecharacteristics relative to the extreme pressure properties of alubricating oil are provided when minor proportions of a sulfurized andphosphorized terpene and an oil soluble alkali metal organic sulfonateare admixed in a mineral oil base.

The sulfurizecl and phosphorized terpene alcohol employed inillustrating the instant invention was prepared by slowly heating onemole of a bicyclic terpene alcohol, methylol beta pinene, having aformula CuHrzOH, to a temperature of approximately 270 F. An equimolarproportion of pulverulent sulfur was sifted into the heated terpene.After the addition of sulfur the temperature was raised to approximately330 F. and maintained at substantially this temperature until asatisfactory copper strip corrosion test was obtained. In this instanceabout eight hours was required during which period the mixture wascontinuously agitated. The mixture was then allowed to cool to atemperature of about 180 F. About 0.4% by weight of finely dividedphosphorus sesquisulfide was admixed with the sulfurized base and heatapplied to the mixture while it was continuously agitated. Thetemperature was raised to about 220 F. and maintained at about thistemperature until the reaction was completed, about five hours beingsufficient under these conditions. The mixture was then allowed to cool.The finished product was a composition containing 15.7 weight per 4 centsulfur, and 0.22 weight per cent phosphorus and having a viscosity of281 S. U. S. at 210 F.

Although the sulfurization and phosphorization of a terpene alcohol isabove described it will be understood that other substituted orunsubstituted isoprenoids may be employed. For example, camphene,dipentene, pinene, terpineol, isopulegol may be used. Similarly,reasonable latitude may be employed in selecting the other reagents aswell as the amounts used. In preparing the sulfurizedphosphorizedadditive the amount of sulfur may vary within wide limits, dependingupon the terpene being treated. For example, in sulfurizing dipentene asulfurized product containing about 30% by weight of sulfur can beobtained. In carrying out the initial sulfurization reactionsubstantially stoichiometric amounts of sulfur are employed and thesulfurization reaction is carried to substantial completion as evidencedby a negative copper strip test. Any excessive amounts of unusedreactants are separated from the finished product. However, the sulfurcontent of the chemically treated terpene should be sufiicient toprovide the mineral oil composition containing the sulfurized andphosphorized terpene with an added sulfur content attributable to thepresence of the said terpene of between about 0.2 and 1.8% by weight andprefcrably about 1.25% by weight. Phosphorus compounds such as theoxides, halides, or other sulfides may be used as alternatives in placeof the sesquisulfide. The amount of phosphorus in the sulfurized andphosphorizcd product should not exceed 2 per cent and preferably shouldbe only a fraction of l per cent, preferably 0.2 to 0.6 per cent basedon the weight of sulfurized base.

The sulfonates which are admixed in the mineral oil base in combinationwith the sulfurized and phosphorized terpene may be any oil solublealkali metal salt of sulfonic acid. The alkali metal petroleumsulfonates however are preferred.

What is claimed is:

l. A lubricating composition comprising a mineral oil base havingadmixed therein minor proportions of a sulfurized-phosphorized terpenealcohol in an amount suflicient to impart anti-wear characteristics tosaid mineral oil and an oil soluble alkali metal organic sulfonate in anamount sufiicient to enhance the effectiveness of said alcohol as ananti-wear agent.

2. A composition in accordance with claim 1 in which said sulfonate is asodium petroleum sulfonate.

3. A mineral oil lubricating composition having enhanced anti-wearproperties which contains an amount of a sulfurized and phosphorizedterpene alcohol suflicient to provide said composition with an addedsulfur content attributable to said terpene of between about 0.2 to 1.8per cent by weight, and about 0.5 to 5 per cent by weight based on totalcomposition of an oil soluble alkali metal organic sulfonate.

4. A composition in accordance with claim 3' in which about 1 per centby weight of said su'lfonate is present.

5. A lubricating composition which comprises a mineral oil containingabout 8.5 per cent by weight of a phosphorized and sulfurized methylolbeta pinene and l per cent by weight of a sodium petroleum sulfonatebased on total composition, said sulfurized-phosphorized pincnecontaining about 16 per cent by weight of sulfur and about 0.2 to 0.25per cent by weight of phosphorus based on said pinene.

References Cited in the file of this patent UNITED STATES PATENTS

1. A LUBRICATING COMPOSITION A MINERAL OIL BASE HAVING ADMIXED THEREINMINOR PROPORTIONS OF A SULFURIZED-PHOSPHORIZED TERPENE ALCOHOL IN ANAMOUNT SUFFICIENT TO IMPART ANTI-WEAR CHARACTERISTICS TO SAID MINERALOIL AND AN OIL SOLUBLE ALKALI METAL ORGANIC SULFONATE IN AN AMOUNTSUFFICIENT TO ENHANCE THE EFFECTIVENESS OF SAID ALCOHOL AS AN ANTI-WEARAGENT.